A technology for recognizing denomination, authenticity, and fitness of a banknote by analyzing the optical characteristics of the banknote, obtained by emitting a light toward the banknote and measuring a reflected light reflected from the surface of the banknote or a transmitted light transmitted through the banknote, is known in the art. For example, Patent Document 1 discloses a banknote recognition apparatus that measures the optical characteristics of a banknote by using plural types of light sources aligned in a line, including ultraviolet light sources or infrared light sources, and sensors arranged corresponding to these light sources. On the other hand, Patent Document 2 discloses a device that recognizes a banknote by generating two reflected lights of different wavelength bands by filtering an ultraviolet light reflected from the surface of the banknote, measuring these reflected lights at respective sensors, and subjecting the measurement result to spectral analysis.
If a banknote has optical characteristics for an ultraviolet light or an infrared light, then it is possible to recognize this banknote by emitting the ultraviolet light or the infrared light toward the banknote and analyzing intensities of a reflected light or a transmitted light obtained from the banknote. On the other hand, if there are plural types of banknotes as the processing targets, these banknotes can be recognized by analyzing their spectral distributions if a spectral distribution of a reflected light or a transmitted light obtained from these banknotes when these banknotes are being irradiated with an ultraviolet light or an infrared light is different per denomination. Because such optical characteristics are measured in each of a plurality of partial regions on the banknote, plural light sources, each of which can emit an inspection light of a specific wavelength toward each of the partial regions, are arranged, and plural sensors are arranged corresponding to the plural light sources. Recognition of the banknote is performed by using the data obtained by these sensors.